59 research outputs found
English loanwords in modern Russian language
English loanwords are presently entering the Russian language, often replacing their native counterparts. This thesis addresses the question of why Russian speakers adopt English loanwords instead of using the existing native counterparts. By utilizing content analysis of word frequency data from the Russian national corpus, this thesis demonstrates that loanwords and their counterparts often have some semantic differences. These differences are revealed by examining the meaning and frequency of adjectives collocated with loanwords and their counterparts. Some adjectives are more likely to collocate with a loanword but not its counterpart, often resulting in narrowing of originally broad loanword meaning into a niche meaning. When an English loanword and its Russian counterpart have different meanings, the loanword has an advantage in lexical competition, and is therefore more likely to be adopted and used by Russian speakers. This thesis presents an objective and quantifiable method of determining such an advantage
Arsenic Exposure and Type 2 Diabetes: MicroRNAs as Mechanistic Links?
PURPOSE OF REVIEW: The goal of this review is to delineate the following: (1) the primary means of inorganic arsenic (iAs) exposure for human populations, (2) the adverse public health outcomes associated with chronic iAs exposure, (3) the pathophysiological connection between arsenic and type 2 diabetes (T2D), and (4) the incipient evidence for microRNAs as candidate mechanistic links between iAs exposure and T2D.
RECENT FINDINGS: Exposure to iAs in animal models has been associated with the dysfunction of several different cell types and tissues, including liver and pancreatic islets. Many microRNAs that have been identified as responsive to iAs exposure under in vitro and/or in vivo conditions have also been shown in independent studies to regulate processes that underlie T2D etiology, such as glucose-stimulated insulin secretion from pancreatic beta cells. Defects in insulin secretion could be, in part, associated with aberrant microRNA expression and activity. Additional in vivo studies need to be performed with standardized concentrations and durations of arsenic exposure in order to evaluate rigorously microRNAs as molecular drivers of iAs-associated diabetes
Methylarsonous Acid Transport by Aquaglyceroporins
Many mammals methylate trivalent inorganic arsenic in liver to species that are released into the bloodstream and excreted in urine and feces. This study addresses how methylated arsenicals pass through cell membranes. We have previously shown that aquaglyceroporin channels, including Escherichia coli GlpF, Saccharomyces cerevisiae Fps1p, AQP7, and AQP9 from rat and human, conduct trivalent inorganic arsenic [As(III)] as arsenic trioxide, the protonated form of arsenite. One of the initial products of As(III) methylation is methylarsonous acid [MAs(III)], which is considerably more toxic than inorganic As(III). In this study, we investigated the ability of GlpF, Fps1p, and AQP9 to facilitate movement of MAs(III) and found that rat aquaglyceroporin conducted MAs(III) at a higher rate than the yeast homologue. In addition, rat AQP9 facilitates MAs(III) at a higher rate than As(III). These results demonstrate that aquaglyceroporins differ both in selectivity for and in transport rates of trivalent arsenicals. In this study, the requirement of AQP9 residues Phe-64 and Arg-219 for MAs(III) movement was examined. A hydrophobic residue at position 64 is not required for MAs(III) transport, whereas an arginine at residue 219 may be required. This is similar to that found for As(III), suggesting that As(III) and MAs(III) use the same translocation pathway in AQP9. Identification of MAs(III) as an AQP9 substrate is an important step in understanding physiologic responses to arsenic in mammals, including humans
Biological and behavioral factors modify urinary arsenic metabolic profiles in a U.S. population
Abstract Background Because some adverse health effects associated with chronic arsenic exposure may be mediated by methylated arsenicals, interindividual variation in capacity to convert inorganic arsenic into mono- and di-methylated metabolites may be an important determinant of risk associated with exposure to this metalloid. Hence, identifying biological and behavioral factors that modify an individual’s capacity to methylate inorganic arsenic could provide insights into critical dose-response relations underlying adverse health effects. Methods A total of 904 older adults (≥45 years old) in Churchill County, Nevada, who chronically used home tap water supplies containing up to 1850 μg of arsenic per liter provided urine and toenail samples for determination of total and speciated arsenic levels. Effects of biological factors (gender, age, body mass index) and behavioral factors (smoking, recent fish or shellfish consumption) on patterns of arsenicals in urine were evaluated with bivariate analyses and multivariate regression models. Results Relative contributions of inorganic, mono-, and di-methylated arsenic to total speciated arsenic in urine were unchanged over the range of concentrations of arsenic in home tap water supplies used by study participants. Gender predicted both absolute and relative amounts of arsenicals in urine. Age predicted levels of inorganic arsenic in urine and body mass index predicted relative levels of mono- and di-methylated arsenic in urine. Smoking predicted both absolute and relative levels of arsenicals in urine. Multivariate regression models were developed for both absolute and relative levels of arsenicals in urine. Concentration of arsenic in home tap water and estimated water consumption were strongly predictive of levels of arsenicals in urine as were smoking, body mass index, and gender. Relative contributions of arsenicals to urinary arsenic were not consistently predicted by concentrations of arsenic in drinking water supplies but were more consistently predicted by gender, body mass index, age, and smoking. Conclusions These findings suggest that analyses of dose-response relations in arsenic-exposed populations should account for biological and behavioral factors that modify levels of inorganic and methylated arsenicals in urine. Evidence of significant effects of these factors on arsenic metabolism may also support mode of action studies in appropriate experimental models
Biological and behavioral factors modify urinary arsenic metabolic profiles in a U.S. population
Abstract Background Because some adverse health effects associated with chronic arsenic exposure may be mediated by methylated arsenicals, interindividual variation in capacity to convert inorganic arsenic into mono- and di-methylated metabolites may be an important determinant of risk associated with exposure to this metalloid. Hence, identifying biological and behavioral factors that modify an individual’s capacity to methylate inorganic arsenic could provide insights into critical dose-response relations underlying adverse health effects. Methods A total of 904 older adults (≥45 years old) in Churchill County, Nevada, who chronically used home tap water supplies containing up to 1850 μg of arsenic per liter provided urine and toenail samples for determination of total and speciated arsenic levels. Effects of biological factors (gender, age, body mass index) and behavioral factors (smoking, recent fish or shellfish consumption) on patterns of arsenicals in urine were evaluated with bivariate analyses and multivariate regression models. Results Relative contributions of inorganic, mono-, and di-methylated arsenic to total speciated arsenic in urine were unchanged over the range of concentrations of arsenic in home tap water supplies used by study participants. Gender predicted both absolute and relative amounts of arsenicals in urine. Age predicted levels of inorganic arsenic in urine and body mass index predicted relative levels of mono- and di-methylated arsenic in urine. Smoking predicted both absolute and relative levels of arsenicals in urine. Multivariate regression models were developed for both absolute and relative levels of arsenicals in urine. Concentration of arsenic in home tap water and estimated water consumption were strongly predictive of levels of arsenicals in urine as were smoking, body mass index, and gender. Relative contributions of arsenicals to urinary arsenic were not consistently predicted by concentrations of arsenic in drinking water supplies but were more consistently predicted by gender, body mass index, age, and smoking. Conclusions These findings suggest that analyses of dose-response relations in arsenic-exposed populations should account for biological and behavioral factors that modify levels of inorganic and methylated arsenicals in urine. Evidence of significant effects of these factors on arsenic metabolism may also support mode of action studies in appropriate experimental models
Metabolic Phenotype of Wild-Type and As3mt-Knockout C57BL/6J Mice Exposed to Inorganic Arsenic: The Role of Dietary Fat and Folate Intake
BACKGROUND: Inorganic arsenic (iAs) is a diabetogen. Interindividual differences in iAs metabolism have been linked to susceptibility to diabetes in iAs-exposed populations. Dietary folate intake has been shown to influence iAs metabolism, but to our knowledge its role in iAs-associated diabetes has not been studied. OBJECTIVE: The goal of this study was to assess how folate intake, combined with low-fat (LFD) and high-fat diets (HFD), affects the metabolism and diabetogenic effects of iAs in wild-type (WT) mice and in As3mt-knockout (KO) mice that have limited capacity for iAs detoxification. METHODS: Male and female WT and KO mice were exposed to 0 or [Formula: see text] iAs in drinking water. Mice were fed the LFD containing [Formula: see text] or [Formula: see text] folate for 24 weeks, followed by the HFD with the same folate levels for 13 weeks. Metabolic phenotype and iAs metabolism were examined before and after switching to the HFD. RESULTS: iAs exposure had little effect on the phenotype of mice fed LFD regardless of folate intake. High folate intake stimulated iAs metabolism, but only in WT females. KO mice accumulated more fat than WT mice and were insulin resistant, with males more insulin resistant than females despite similar %fat mass. Feeding the HFD increased adiposity and insulin resistance in all mice. However, iAs-exposed male and female WT mice with low folate intake were more insulin resistant than unexposed controls. High folate intake alleviated insulin resistance in both sexes, but stimulated iAs metabolism only in female mice. CONCLUSIONS: Exposure to [Formula: see text] iAs in drinking water resulted in insulin resistance in WT mice only when combined with a HFD and low folate intake. The protective effect of high folate intake may be independent of iAs metabolism, at least in male mice. KO mice were more prone to developing insulin resistance, possibly due to the accumulation of iAs in tissues. https://doi.org/10.1289/EHP3951
Tissue dosimetry, metabolism and excretion of pentavalent and trivalent monomethylated arsenic in mice after oral administration
Exposure to monomethylarsonic acid (MMA(V)) and monomethylarsonous acid (MMA(III)) can result from their formation as metabolites of inorganic arsenic and by the use of the sodium salts of MMA(V) as herbicides. This study compared the disposition of MMA(V) and MMA(III) in adult female B6C3F1 mice. Mice were gavaged po with MMA(V), either unlabeled or labeled with 14C at two dose levels (0.4 or 40 mg As/kg). Other mice were dosed po with unlabeled MMA(III) at one dose level (0.4 mg As/kg). Mice were housed in metabolism cages for collection of excreta and sacrificed serially over 24 h for collection of tissues. MMA(V)-derived radioactivity was rapidly absorbed, distributed and excreted. By 8 h post-exposure, 80% of both doses of MMA(V) were eliminated in urine and feces. Absorption of MMA(V) was dose dependent; that is, there was less than a 100-fold difference between the two dose levels in the area under the curves for the concentration-time profiles of arsenic in blood and major organs. In addition, urinary excretion of MMA(V)-derived radioactivity in the low dose group was significantly greater (P < 0.05) than in the high dose group. Conversely, fecal excretion of MMA(V)-derived radioactivity was significantly greater (P < 0.05) in the high dose group than in the low dose group. Speciation of arsenic by hydride generation-atomic absorption spectrometry in urine and tissues of mice administered MMA(V) or MMA(III) found that methylation of MMA(V) was limited while the methylation of MMA(III) was extensive. Less than 10% of the dose excreted in urine of MMA(V)-treated mice was in the form of methylated products, whereas it was greater than 90% for MMA(III)-treated mice. In MMA(V)-treated mice, 25% or less of the tissue arsenic was in the form of dimethylarsenic, whereas in MMA(III)-treated mice, 75% or more of the tissue arsenic was in the form of dimethylarsenic. Based on urinary analysis, administered dose of MMA(V) did not affect the level of its metabolites excreted. In the tested range, dose affects the absorption, distribution and route of excretion of MMA(V) but not its metabolism
Arsenicals in maternal and fetal mouse tissues after gestational exposure to arsenite
Exposure of pregnant C3H/HeNCR mice to 42.5- or 85-ppm of arsenic as sodium arsenite in drinking water between days 8 and 18 of gestation markedly increases tumor incidence in their offspring. In the work reported here, distribution of inorganic arsenic and its metabolites, methyl arsenic and dimethyl arsenic, were determined in maternal and fetal tissues collected on gestational day 18 of these exposure regimens. Tissues were collected from three females and from associated fetuses exposed to each dosage level. Concentrations of total speciated arsenic (sum of inorganic, methyl, and dimethyl arsenic) were higher in maternal tissues than in placenta and fetal tissues; total speciated arsenic concentration in placenta exceeded those in fetal tissues. Significant dosage-dependent (42.5 ppm versus 85 ppm of arsenite in drinking water) differences were found in total speciated arsenic concentrations in maternal lung (p < 0.01) and liver (p < 0.001). Total speciated arsenic concentrations did not differ significantly between dosage levels for maternal blood or for fetal lung, liver, and blood, or for placenta. Percentages of inorganic, methyl, or dimethyl arsenic in maternal or fetal tissues were not dosage-dependent. Over the range of total speciated arsenic concentrations in most maternal and fetal tissues, dimethyl arsenic was the most abundant arsenical. However, in maternal liver at the highest total speciated arsenic concentration, inorganic arsenic was the most abundant arsenical, suggesting that a high tissue burden of arsenic affected formation or retention of methylated species in this organ. Tissue concentration-dependent processes could affect kinetics of transfer of inorganic arsenic or its metabolites from mother to fetus
Arsenic-induced malignant transformation of human keratinocytes: Involvement of Nrf2
Arsenic is a well-known human skin carcinogen but the underlying mechanisms of carcinogenesis are unclear. Transcription factor Nrf2-mediated antioxidant response represents a critical cellular defense mechanism, and emerging data suggest that constitutive activation of Nrf2 contributes to malignant phenotype. In the present study when an immortalized, non-tumorigenic human keratinocyte cell line (HaCaT) was continuously exposed to environmentally relevant level of inorganic arsenite (100 nM) for 28 weeks, malignant transformation occurred as evidenced by the formation of highly aggressive squamous cell carcinoma after inoculation into nude mice. To investigate the mechanisms involved, a broad array of biomarkers for transformation were assessed in these arsenic-transformed cells (termed As-TM). In addition to increased secretion of matrix metalloproteinase-9 (MMP-9), a set of markers for squamous differentiation and skin keratinization, including keratin-1, keratin-10, involucrin, and loricrin, were significantly elevated in As-TM cells. Furthermore, As-TM cells showed increased intracellular glutathione, elevated expression of Nrf2 and its target genes, as well as generalized apoptotic resistance. In contrast to increased basal Nrf2 activity in As-TM cells, a diminished Nrf2-mediated antioxidant response induced by acute exposure to high dose of arsenite or tert-butyl hydroxyquinone occurred. The findings that multiple biomarkers for malignant transformation observed in As-TM cells, including MMP-9 and cytokeratins, are potentially regulated by Nrf2 suggest constitutive Nrf2 activation may be involved in arsenic carcinogenesis of skin. The weakened Nrf2 activation in response to oxidative stressors observed in As-TM cells, coupled with acquired apoptotic resistance, would potentially have increased the likelihood of transmittable oxidative DNA damage and fixation of mutational/DNA damage events
- …